There is currently a growing interest in biopolymers, such as bacterial cellulose and thermoplastic starch, which are renewable and abundantly available in nature. This study investigated the multilayer sandwich composite with thermoplastic starch and bacterial cellulose, using water (TPS/BC-w) and glycerol (TPS/BC-g) as coupling agents. The composites produced by compression molding resulted in a homogeneous, transparent and flexible structure. TPS/BC-w showed superior mechanical property and better adhesion compared to TPS/BC-g. Therefore, the permeability, biodegradation, hydrothermal aging and stability analyses were conducted only for TPS/ BC-w. The water vapor permeability of TPS/BC-w is 6.7 times lower than that of thermoplastic starch, indicating better barrier performance. Thermoplastic starch and bacterial cellulose degraded in about 9 days, and TPS/BCw degraded in 60 days. Biodegradation analysis by COQ release confirmed the complete biodegradation process, with COQ emissions of 57 %, 42.5 % and 39.6 % after 120 days for thermoplastic starch, bacterial cellulose and TPS/BC-w, respectively. TPS/BC-w remained intact for more than a year, in an environment without direct contact with soil or water. These results indicate that TPS/BC-w composed of natural macromolecules may exhibit functional properties and is useful for applications such as short-shelf-life packaging, particularly for dry products, due to its barrier properties and controlled biodegradability.

Bacterial cellulose (BC), known for its exceptional physical properties and sustainability, has garnered widespread attention as a promising alternative to petrochemical-based plastic packaging. However, application of BC for packaging remains limited due to its hygroscopic nature, poor food preservation capabilities, and low optical transparency. In this study, a novel in-situ spraying method for chitosan (CS) encapsulation was developed to fabricate BC/CS hybrid structure layer by layer. The resulting composites exhibit effective antimicrobial activity against both Gram-positive and Gram-negative (> 75 %) bacteria, ensuring food preservation and safety. The BC/CS composites were modified through mercerization and heat drying (mBC/CS), transforming the cellulose crystal structure from cellulose I to the more stable cellulose II and inducing the alignment of a compact structure. Following waterborne polyurethane (WPU) coating, the mBC/CS/WPU composites acquired hydrophobic and heat-sealable properties, along with an 80 % reduction in haze and light transmittance exceeding 85 %. Further, they exhibited exceptional mechanical properties, including an ultimate tensile strength exceeding 200 MPa and omnidirectional flexibility. These composites could also preserve the freshness of sliced apples (< 20 % weight loss) and poached chicken (< 3 % weight loss) after one week of storage, comparable to commercial zipper bags, and also prevent food contamination. Notably, the mBC/CS/WPU composites displayed no ecotoxicity during decomposition and degraded completely within 60 days in soil. This study provides a valuable framework for functionalizing BC-based materials, promoting sustainable packaging, and contributing to the mitigation of plastic pollution.

Innovative materials for sustainable applications are of increasing interest in scientific research. The practicality of bacterial cellulose (BC) derived aerogels could be enhanced if they could fulfill the required mechanical property for applications. In this study, double-network aerogels composed of BC and cotton fibers (CF) were fabricated using the directional ice-templated method. The impact of different CF contents on the interfacial and structural properties of the BC/CF aerogels was investigated. With the introduction of CF, the mechanical properties of BC/CF aerogels were improved. With 33 % CF addition, the compressive strength of BC/CF aerogels reached a maximum value and achieved 34.2 kPa along the parallel (a) direction, which is 110 % higher than that of pristine BC aerogel (16.2 kPa). With the introduction of methyl trimethoxy silane (MTMS), the mechanical properties and elasticity were further enhanced (97.2 kPa). Furthermore, the hybrid aerogels also demonstrated excellent thermal insulation and air filtration properties, A thermal conductivity of 26.0 mW/m.K along the perpendicular (p) direction and a quality factor (QF) of 0.081 Pa-1 were achieved. Notably, the hybrid aerogels exhibited excellent biodegradation performance in soil burial tests. These results open up new avenues for the development of BC derived aerogels, and position them as a sustainable alternative to filtration and thermal insulation materials.

The interest of reinventing raw earth is for the purpose of drastically reducing the environmental impact of the continuous human urban growth. This paper discusses the use of cellulose synthesized by bacteria as a new source of microfibers to reinforce the soil matrix. It presents firstly, the bacterial cellulose (BC) and its production method then it focuses on defining its microstructural characteristics. In the second part, the soil-BC association is studied. Commercial soil (DW-earth) and bentonite clay were tested with 3 and 8% of BC. The objective is to evaluate the impact of BC addition on the soil's physcio -mechanical properties. Shrinkage and mechanical performance tests were carried out. The results showed a material with better mechanical performances and high cracks resistance. The shrinkage percentage decreased significantly for DW-earth with a similar water/solid ratio when adding BC, by about 18 and 22% when adding 3 and 8% BC for water content of 35%. In the case of bentonite clay the BC addition has only a positive impact on limiting cracking. The mechanical tests showed that 8% of BC increases the compressive strength of the cylindrical specimens by + 28 and + 649%, respectively for the DW-earth and bentonite clay, whereas the flexural strength of the prismatic specimens increases by + 39 and + 556%.